Process for auxiliary powder supply in autogeneous metal processing and device therefor



1970 HANSJOACHIM WERNICKE PROCESS FOR AUXILIARY POWDER SUPPLY IN AUTOGENEOUS METAL PROCESSING AND DEVICE THEREFOR Filed Nov. 22, 1966 United States Patent M 67,380 Int. Cl. B23k 7/00, 7/06 US. Cl. 148-9.5 12 Claims ABSTRACT OF THE DISCLOSURE A flame scarfing torch including a nozzle having an inclined oxygen stream for directing oxygen against a metal surface at an acute angle thereto. An auxiliary powder passageway is inclined within the acute angle to aid in the flame scarfing operation.

The invention relates to a process for supplying slag flow forming auxiliary powder in the reaction zone in autogeneous metal processing with an oxygen stream arranged at an incline, such as in flame scarfing; and to a device for carrying out this process.

In a known flame scarfing torch described in German Patent 1,016,102, an auxiliary powder supply is provided which terminates above the oxygen stream supply, i.e. on the side of the oxygen stream remote from the metal surface to be treated. The auxiliary powder, which is usually iron powder, is also blown into the flame from the reverse side of the work piece surface to be treated and must completely cross the flame in order to reach the reaction zone situated on the other side of the flame. Fuel gases and oxygen travel with considerable speed in the area of the flame. However, this speed of travel in the area of the reaction zone is directed essentially parallel to the work piece surface. This current or path of travel traverses the path which the auxiliary powder must take in this known flame scarfing torch, and the auxiliary powder, being at least partially deflected from the original direction by these streaming gases, is carried away with the flame; thus being unable to reach the reaction zone. This can be counteracted by blowing the auxiliary powder into the flame with a corresponding aiming-off allowance and with a strong carrier gas stream. As a rule, however, the carrier gas stream is disadvantageous in this connection, because it hinders the formation of the flame and of the reaction zone, especially if it is very strong, If the stream is weak, then the desired effect is only partially achieved. But even with such a carrier stream, the known device does not succeed in delivering the greatest part of the auxiliary powder into the reaction zone. A considerable part is carried away by the flame without any effect. As a result, in this known torch it is necessary to constantly supply more auxiliary powder than is actually required in the reaction zone.

The object of the invention is to provide a process and a device of the above-named type in such a manner that the auxiliary powder is brought into the reaction zone as completely as possible and without disturbing the formation of the reaction zone.

The inventive process is characterized in that the auxiliary powder is conducted to the interstice between the oxygen stream and work piece surface. While in the known flame scarfing torch the auxiliary powder must traverse the flame and also the gases streaming there, according to the invention the auxiliary powder is supplied to the side of the flame where the reaction zone is also formed; namely on the side facing the work piece.

3,488,230 Patented Jan. 6, 1970 ice Thus, the auxiliary powder need not traverse the flame, so that the gases streaming there also do not deflect the auxiliary powder from its desired path. These gas currents furthermore enhance the supply of auxiliary powder in the reaction zone, because they stream into the reaction zone and any affect they might have would be to pull the auxiliary powders into the reaction zone, preferably exerting a pull which supports this flow of the auxiliary powder in the reaction zone.

The auxiliary powder can be conducted by means of a carrier gas stream, according to the process of the invention. However, such a carrier gas stream by far does not require the energy which a carrier gas stream requires in a conventional flame scarfing torch, because this carrier gas stream is not traversed by other gas streams on the way to the reaction zone. In many instances, such a carrier gas stream is entirely unnecessary and the auxiliary powder itself can be sprayed into the interstice. As a rule, this interstice, without requiring any special provisions, is not shielded to be gas tight in the back, so that the gases streaming in the flame build up a suction in this interstice which is continuously filled from the air. By means of the resulting current which is directed into the reaction zone, the auxiliary powder which has been sprayed only in the interstice is then pulled along.

The supply of auxiliary powder suitably takes place at an inclination to the metal surface such as that of the oxygen stream, or in other words: the direction in which the auxiliary powder is conducted-aside from the slant to the work piece suifaceis the same as that in which the oxygen stream is conducted. In such a case, the cooperation produced by the oxygen stream and the fuel gases is highest with the addition of the auxiliary powder into the reaction zone.

The statements made above refer to the operating conditions of a torch where the flame is already formed. In the starting process, other conditions are present. For example in the starting process the gas streams in the flame are much slighter. It is then also entirely possible to supply the auxiliary powder in the manner of the initially described known device, while gas streams worth mentioning which then cross the path of the auxiliary powder are not present. On the other side, a suction effect in the interstice is lacking in the starting process, simply because the gas streams which effect this suction are not yet present in their entirety. On this basis it is recommended to supply the auxiliary powder in the starting process at least, with a partial amount outside the interstice. In the starting process the auxiliary powder must be brought into the so-called ignition zone, which is located directly before the torch nozzle. Also on this basis, it is recommended to supply auxiliary powder in the starting process from outside the interstice. As soon as ignition is achieved in the course of the starting process and the gas stream is increased, the conditions are changed, and the supply of the auxiliary powder from outside the interstice becomes increasingly diflicult because of the gas streams. These circumstances are equalized by the preferred process of the invention, which is characterized in that in the first phase of the initial process the auxiliary powder is supplied exclusively outside the interstice, in the second phase of the starting process the powder is supplied from both sides of the oxygen stream, and finally during the flame spraying process the powder is supplied exclusively in the interstice.

The invention is preferably usable in flame scarfing. A flame scarfing torch with an auxiliary powder supply directed into the reaction zone is inventively characterized by the auxiliary powder supply conduit terminating at the work piece side of the oxygen stream supply line. The

auxiliary powder then reaches into the interstice between the oxygen stream and the work piece and in this interstice into the reaction zone. If in the starting process, because of the reasons indicated above, the auxiliary powder is conducted from outside this interstice, then the supply takes place during the starting process from a side other than that during the work process. The auxiliary powder supply conduit here could be made movable. However, this is not preferred because of the expenditure involved. A flame scarfing design is suitable which is characterized by a second auxiliary powder supply conduit which terminates at the other side of the oxygen stream supply opposite the first auxiliary powder conduit. The one auxiliary powder conduit then terminates in the interstice and conducts the auxiliary powder during the torch process, while the other auxiliary powder conduit terminates outside this interstice, so that through this second auxiliary powder conduit the axuiliary powder is supplied during the starting process. When a torch according to the abovedescribed preferred process is operated, then in the first phase of the statring process only the supplemental auxiliary powder conduit is charged. At the end of the first phase of the starting process, the charging of this additional auxiliary powder conduit is bafiied and the auxiliary powder conduit terminating in the interstice is partially charged. At the end of the starting process, (i.e. when the reaction is completely started) the charging of the supplemental auxiliary powder conduit is switched off, and the auxiliary powder conduit terminating in the interstice is completely charged.

The invention is explained in more detail by way of the attached drawing, which shows a preferred design of a torch in cross-section during the normal flame scarfing operation.

In the drawing, the nozzle part 1 of a flame scarfing head has its oxygen stream 2 directed at a slant to the surface 3 of a metal work piece 4 to be treated. Two preheated gas flames 5 and 6 are extended above and below the oxygen stream 2. The reaction zone in which the flame scarfing process affects the metal surface 3 is designated by reference character 7.

In this reaction zone 7, iron powder is needed as auxiliary powder. For supplying this iron powder, supply conduit 8 is provided, according to the invention, which terminates below the torch head 1. Torch head 1 supported on tracks 9, slides on the work piece surface 3 so that a narrow slot 10 remains between the head 1 and "work surface 3. This slot terminates in an interstice 11,

which is bounded above by the oxygen stream 2 and below by the work piece 4. In this interstice 11 the gases streaming in the front part of the torch 1 form a vacuum which continues in the slot 10 and which draws in the iron powder supply by way of the supply conduit 8 and pulls it into the reaction zone 7. A second auxiliary powder supply conduit is designated by 13 and has a supply conduit 14 which terminates above the oxygen stream at 15. During the starting process, iron powder is blown into the ignition zone by way of this supply conduit 14, the iron powder being conducted in a carrier gas stream.

Obviously many variations and modifications are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described.

What is claimed is:

1. A process for supplying auxiliary powder in the reaction zone in autogeneous metal processing with an oxygen stream directed at an angle to the work piece surface, characterized in conducting the auxiliary powder in the interstice between the oxygen stream and the work piece surface, during the starting phase of the process the auxiliary powder being supplied exclusive outside the interstice, the powder being supplied from both sides of the oxygen stream in a later phase of the process, and the powder then being supplied exclusively in the interstice.

2. In a process for supplying auxiliary powder in the reaction zone in autogeneous metal processing including directing an oxygen stream against the metal surface at an acute angle thereto, directing auxiliary powder from a pas: sageway within the acute angle toward the metal surface prior to the reaction zone, and conveying the auxiliary powder from the passageway over the metal surface into the reaction zone.

3. In a process of claim 2 wherein the powder is supplied from the passageway at the same angle as the oxygen stream.

4. In the process of claim 2 including supplying auxiliary powder toward the reaction zone outside of the acute angle during the starting phase of the process.

5. In the process of claim 4 including also supplying auxiliary powder within the acute angle during the sta'rting of the process. I

6. In a flame scarfing torch for flame spraying metal surfaces, including-a nozzle, an inclined oxygen stream conduit for directing oxygen against the metal surface at a reaction zone, in a processing direction to form an acute angle with respect to the metal surface, and an auxiliary powder passageway connected to an auxiliary power source in said nozzle inclined within said acute angle in the processing direction between said oxygen conduit and the metal surface.

7. In the torch of claim 6 wherein said auxiliary powder passageway is inclined to discharge the powder against the metal surface prior to the reaction zone with the powder then being carried into the reaction zone.

8. In the torch of claim 7 including fuel gas passages directed toward the reaction zone for sucking the powder into the reaction zone.

9. In the torch of claim 7 wherein said auxiliary powder passageway is inclined at the same angle as said oxygen conduit.

10. In the torch of claim 7 including a second auxiliary powder passageway in said nozzle, said oxygen conduit being disposed between the first and said second powder passageways.

11. In the torch of claim 7 including a second auxiliary powder passageway in said nozzle inclined outside of said acute angle. k

12. In the torch of claim 7 including means for mounting said nozzle with respect to the metal surface whereby said oxygen conduit is maintained at said acute angle and a narrow slot is formed by the nozzle and metal surface leading from the outlet of said auxiliary powder passageway to the reaction zone.

References Cited UNITED STATES PATENTS 2,438,344 3 /1948 Meincke 266-23 2,317,93 6 4/ 1943 Nicholson et al 266--23 FOREIGN PATENTS 637,816 5/ 1950 Great Britain.

L. DEWAYNE RUTLEDGE, Primary Examiner W. W. STALLARD, Assistant Examiner U.S. Cl. X.R. 

